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目录

课后习题

习题1

#include 
   
    #include 
    
     using namespace std;class Cow {	char name[20];	char * hobby;	double weight;public:	Cow();	Cow(const char * nm, const char * ho, double wt);	Cow(const Cow & C);	~Cow();	void ShowCow() const;};Cow::Cow() {}Cow::Cow(const char * nm, const char * ho, double wt){	strcpy(name, nm);	hobby = new char[strlen(ho) + 1];	strcpy(hobby, ho);	weight = wt;}Cow::Cow(const Cow & C){	strcpy(name, C.name);	hobby = new char[strlen(C.hobby) + 1];	strcpy(hobby, C.hobby);	weight = C.weight;}Cow::~Cow() { delete[] hobby; }void Cow::ShowCow() const{	cout << name << endl;	cout << hobby << endl;	cout << weight << endl;}int main(){	Cow cow;	Cow ccc("adads", "dsdfsad", 34);	cow = ccc;	cow.ShowCow();	ccc.ShowCow();}
    
   

习题2

#include 
   
    #include 
    
     #include 
     
      using namespace std;class String{	char* mp_text;	unsigned m_text_length;	void assignMember(const char* text)	{		m_text_length = strlen(text);		mp_text = new char[m_text_length + 1];		strcpy(mp_text, text);	}public:	static const unsigned k_buffer_max_size = 256;	const char* toCstr() const	{		return (mp_text);	}	String(const char* text = "")	{		assignMember(text);	}	String(const String& str)	{		assignMember(str.toCstr());	}	~String()	{		delete[] mp_text;	}	unsigned getLength() const	{		return (m_text_length);	}	void stringup()	{		for (unsigned i = 0; i < m_text_length; ++i)			mp_text[i] = (char)toupper(mp_text[i]);	}	void stringlow()	{		for (unsigned i = 0; i < m_text_length; ++i)			mp_text[i] = (char)tolower((int)mp_text[i]);	}	unsigned has(char ch) const	{		unsigned cnt = 0;		for (unsigned i = 0; i < m_text_length; ++i)			if (ch == mp_text[i])				++cnt;		return (cnt);	}	String& operator= (const String& str)	{		if (&str == this)			return (*this);		delete[] mp_text;		assignMember(str.toCstr());		return (*this);	}	String & operator+= (const String& str)	{		return (*this += str);	}	char& operator[] (unsigned idx)	{		return (mp_text[idx]);	}	const char & operator[] (unsigned idx) const	{		return (mp_text[idx]);	}	friend ostream & operator<< (ostream& os, const String& str)	{		os << str.toCstr();		return (os);	}	friend istream & operator>> (istream& is, String& str)	{		char txt[k_buffer_max_size];		if (is >> txt)			str = txt;		is.ignore(k_buffer_max_size, '\n');		return (is);	}	friend bool operator< (const String& lvalue, const String& rvalue)	{		return (strcmp(lvalue.toCstr(), rvalue.toCstr()) < 0);	}	friend bool operator> (const String& lvalue, const String& rvalue)	{		return (rvalue < lvalue);	}	friend bool operator== (const String& lvalue, const String& rvalue)	{		return (!(lvalue < rvalue) && !(lvalue > rvalue));	}	friend bool operator<= (const String& lvalue, const String& rvalue)	{		return (!(lvalue > rvalue));	}	friend bool operator>= (const String& lvalue, const String& rvalue)	{		return (!(lvalue < rvalue));	}	friend String operator+ (const String& lvalue, const String& rvalue)	{		char* p_txt = new char[lvalue.getLength() + rvalue.getLength() + 1];		strcpy(p_txt, lvalue.toCstr());		strcat(p_txt, rvalue.toCstr());		String tmp(p_txt);		delete[] p_txt;		return (tmp);	}};int main(){	String s1(" and I am a C++ student.");	String s2 = "Please enter your name: ";	String s3;	cout << s2;	// overloaded << operator	cin >> s3;	// overloaded >> operator	s2 = "My name is " + s3;	// overloaded =, + operators	cout << s2 << ".\n";	s2 = s2 + s1;	s2.stringup();	// converts string to uppercase	cout << "The string\n" << s2 << "\ncontains " << s2.has('A')		<< " 'A' characters in it.\n";	s1 = "red";	// tstring(const char *),	// then tstring & operator=(const string&)	String rgb[3] = { String(s1), String("green"), String("blue") };	cout << "enter the name of a primary color for mixing light: ";	String ans;	bool success = false;	while (cin >> ans)	{		ans.stringlow();		// converts string to lowercase		for (int i = 0; i < 3; i++)		{			if (ans == rgb[i]) // overloaded == operator			{				cout << "That's right!\n";				success = true;				break;			}		}		if (success)			break;		else			cout << "Try again!\n";	}	cout << "Bye" << endl;}
     
    
   

习题3

#include 
   
    #include 
    
     using namespace std;class Stock{	char *company;	int shares;	double share_val;	double total_val;	void set_tot() { total_val = shares * share_val; };public:	Stock() {		company = new char[8];		strcpy(company, "no name");		shares = 0;		share_val = 0.0;		total_val = 0.0;	}	Stock(const char *co, long n = 0, double pr = 0)	{		int len = strlen(co);		company = new char[len + 1];		strcpy(company, co);		if (n < 0)		{			cout << "Number of shares can't be negative;"				<< company << " shares set to 0" << endl;			shares = 0;		}		else			shares = n;		share_val = pr;		set_tot();	}	~Stock()	{		delete[]company;	}	void buy(long num, double price)	{		if (num < 0)		{			cout << "Number of shares purchase can't be negative."				<< " Transaction is aborted." << endl;		}		else		{			shares += num;			share_val = price;			set_tot();		}	}	void sell(long num, double price)	{		if (num < 0)		{			cout << "Number of shares sold can't be negative."				<< "Transaction is aborted." << endl;		}		else if (num > shares)		{			cout << "You can't sell more than you have!"				<< "Transaction is aborted." << endl;		}		else		{			shares -= num;			share_val = price;			set_tot();		}	}	void update(double price)	{		share_val = price;		set_tot();	}	const Stock &topval(const Stock &s)const	{		if (s.total_val > total_val)			return s;		else			return *this;	}	friend ostream &operator<<(ostream &os, const Stock &s)	{		ios_base::fmtflags orig = os.setf(ios_base::fixed, ios_base::floatfield);		streamsize prec = os.precision(3);		os << "Company:" << s.company			<< " Shares:" << s.shares << endl;		os << " Share Price:$" << s.share_val;		os.precision(2);		os << " Total Worth:&" << s.total_val << endl;		os.setf(orig, ios_base::floatfield);		os.precision(prec);		return os;	}};const int STKS = 4;int main(){	// create an array of initialized objects	Stock stocks[STKS] = {	Stock("NanoSmart", 12, 20.0),	Stock("Boffo Objects", 200, 2.0),	Stock("Monolithic Obelisks", 130, 3.25),	Stock("Fleep Enterprises", 60, 6.5)	};	cout << "Stock holdings:\n";	int st;	for (st = 0; st < STKS; st++)		cout << stocks[st];	// set pointer to first element	const Stock * top = &stocks[0];	for (st = 1; st < STKS; st++)		top = &top->topval(stocks[st]);	// now top points to the most valuable holding	cout << "\nMost valuable holding:\n";	cout << *top;	return 0;}
    
   

习题4

#include 
   
    using namespace std;typedef unsigned long Item;class Stack {	enum { MAX = 10 };	Item * items;	int size;	int top;public:	Stack(int n = MAX)	{		items = new Item[MAX];		top = 0;		size = 0;	}	Stack(const Stack &st)	{		items = new Item[st.size];		top = 0;		size = 0;		for (int i = 0; i < st.size; i++)		{			items[i] = st.items[i];			size++;			top++;		}	}	~Stack()	{		delete[] items;	}	bool isEmpty()	{		return top == 0;	}	bool isFull()	{		return top == MAX;	}	bool push(const Item &it)	{		if (isFull())			cout << "error! Stack is full!" << endl;		else		{			items[top++] = it;			size++;			return true;		}		return false;	}	bool pop(Item &item)	{		if (isEmpty())			cout << "error! Stack is empty!" << endl;		else		{			item = items[top--];			size--;			return true;		}		return false;	}	Stack & operator = (Stack &st)	{		delete[] items;		items = new Item[st.size];		top = 0;		size = 0;		for (int i = 0; i < st.size; i++)		{			items[i] = st.items[i];			size++;			top++;		}		return (*this);	}	friend ostream & operator<<(ostream &os, const Stack & st)	{		os << "This Stack is:" << endl;		int len = st.top - 1;		while (len != -1)		{			cout << st.items[len] << endl;			len--;		}		return os;	}};int main(){	Stack s;	Item it[20] = { 0 };	for (int i = 0; i < 11; i++)	{		it[i] = i + 1;		s.push(it[i]);	}	cout << s;	Stack s1(s);	cout << "s1=" << s1;	Stack s2 = s;	cout << s;}
   

习题5&6

// queue.h -- interface for a queue#ifndef QUEUE_H_#define QUEUE_H_// This queue will contain Customer itemsclass Customer{private:	long arrive; // arrival time for customer	int processtime; // processing time for customerpublic:	Customer() : arrive(0), processtime(0) {}	void set(long when);	long when() const { return arrive; }	int ptime() const { return processtime; }};typedef Customer Item;class Queue{private:	// class scope definitions	// Node is a nested structure definition local to this class	struct Node { Item item; struct Node * next; };	enum { Q_SIZE = 10 };	// private class members	Node * front; // pointer to front of Queue	Node * rear; // pointer to rear of Queue	int items; // current number of items in Queue	const int qsize; // maximum number of items in Queue	// preemptive definitions to prevent public copying	Queue(const Queue & q) : qsize(0) { }	Queue & operator=(const Queue & q) { return *this; }public:	Queue(int qs = Q_SIZE); // create queue with a qs limit	~Queue();	bool isempty() const;	bool isfull() const;	int queuecount() const;	bool enqueue(const Item &item); // add item to end	bool dequeue(Item &item); // remove item from front};#endif// queue.cpp -- Queue and Customer methods#include "queue.h"#include 
   
     // (or stdlib.h) for rand()// Queue methodsQueue::Queue(int qs) : qsize(qs){	front = rear = NULL;// or nullptr	items = 0;}Queue::~Queue(){	Node * temp;	while (front != NULL) // while queue is not yet empty	{		temp = front; // save address of front item		front = front->next;// reset pointer to next item		delete temp; // delete former front	}}bool Queue::isempty() const{	return items == 0;}bool Queue::isfull() const{	return items == qsize;}int Queue::queuecount() const{	return items;}// Add item to queuebool Queue::enqueue(const Item & item){	if (isfull())		return false;	Node * add = new Node; // create node	// on failure, new throws std::bad_alloc exception	add->item = item; // set node pointers	add->next = NULL; // or nullptr;	items++;	if (front == NULL) // if queue is empty,		front = add; // place item at front	else		rear->next = add; // else place at rear	rear = add; // have rear point to new node	return true;}// Place front item into item variable and remove from queuebool Queue::dequeue(Item & item){	if (front == NULL)		return false;	item = front->item; // set item to first item in queue	items--;	Node * temp = front;// save location of first item	front = front->next;// reset front to next item	delete temp; // delete former first item	if (items == 0)		rear = NULL;	return true;}// customer method// when is the time at which the customer arrives// the arrival time is set to when and the processing// time set to a random value in the range 1 - 3void Customer::set(long when){	processtime = std::rand() % 3 + 1;	arrive = when;}// bank.cpp -- using the Queue interface// compile with queue.cpp#include 
    
     #include 
     
       // for rand() and srand()#include 
      
        // for time()#include "queue.h"const int MIN_PER_HR = 60;bool newcustomer(double x); // is there a new customer?int main(){	using std::cin;	using std::cout;	using std::endl;	using std::ios_base;	// setting things up	std::srand(std::time(0)); // random initializing of rand()	cout << "Case Study: Bank of Heather Automatic Teller\n";	cout << "Enter maximum size of queue: ";	int qs;	cin >> qs;	Queue line(qs); // line queue holds up to qs people	cout << "Enter the number of simulation hours: ";	int hours; // hours of simulation	cin >> hours;	// simulation will run 1 cycle per minute	long cyclelimit = MIN_PER_HR * hours; // # of cycles	cout << "Enter the average number of customers per hour: ";	double perhour; // average # of arrival per hour	cin >> perhour;	double min_per_cust;// average time between arrivals	min_per_cust = MIN_PER_HR / perhour;	Item temp; // new customer data	long turnaways = 0; // turned away by full queue	long customers = 0; // joined the queue	long served = 0; // served during the simulation	long sum_line = 0; // cumulative line length	int wait_time = 0; // time until autoteller is free	long line_wait = 0; // cumulative time in line	// running the simulation	for (int cycle = 0; cycle < cyclelimit; cycle++)	{		if (newcustomer(min_per_cust)) // have newcomer		{			if (line.isfull())				turnaways++;			else			{				customers++;				temp.set(cycle); // cycle = time of arrival				line.enqueue(temp); // add newcomer to line			}		}		if (wait_time <= 0 && !line.isempty())		{			line.dequeue(temp); // attend next customer			wait_time = temp.ptime(); // for wait_time minutes			line_wait += cycle - temp.when();			served++;		}		if (wait_time > 0)			wait_time--;		sum_line += line.queuecount();	}	// reporting results	if (customers > 0)	{		cout << "customers accepted: " << customers << endl;		cout << " customers served: " << served << endl;		cout << " turnaways: " << turnaways << endl;		cout << "average queue size: ";		cout.precision(2);		cout.setf(ios_base::fixed, ios_base::floatfield);		cout << (double)sum_line / cyclelimit << endl;		cout << " average wait time: "			<< (double)line_wait / served << " minutes\n";	}	else		cout << "No customers!\n";	cout << "Done!\n";	// cin.get();	// cin.get();	return 0;}// x = average time, in minutes, between customers// return value is true if customer shows up this minutebool newcustomer(double x){	return (std::rand() * x / RAND_MAX < 1);}
      
     
    
   

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